The present invention relates to imaging devices and, more particularly, to imaging devices with image sensors that may be used to produce high-dynamic-range images.
Image sensors are commonly used in electronic devices such as cellular telephones, cameras, and computers to capture images. In a typical arrangement, an electronic device is provided with a single image sensor having an array of pixels and a single corresponding lens. Some electronic devices use arrays of image sensors and arrays of corresponding lenses.
In certain applications, such as when acquiring still or video images of a scene with a large range of light intensities, it may be desirable to capture high-dynamic range images. While highlight and shadow detail may be lost using a conventional image sensor, highlight and shadow detail may be retained using image sensors with high-dynamic-range capabilities.
Common high-dynamic-range (HDR) imaging systems use a multiple exposure (ME) image capture method. In a ME method, multiple images are captured by the image sensor, each image having a different exposure time. Short-exposure images may retain shadow detail while long-exposure images may retain highlight detail. In a typical device, pixels from short-exposure and long-exposure images are selected to create a HDR image.
When capturing HDR images using ME imaging systems, or any HDR imaging system using sequential exposures, a moving object will be registered at different pixel positions in each exposure. If one of the exposure times in an ME image capture is long relative to the motion of the scene or objects in the scene, object shapes will appear blurred and elongated in the direction of motion in the long exposure image. When the images are combined using conventional multiple exposure HDR image combination methods, the discrepancy in position and shape of a moving object in the multiple exposures will result in misregistration of the object in the combined HDR image.
It would therefore be desirable to provide improved methods of motion-corrected image combination for high-dynamic-range imaging devices.